1. Field of the Invention
The present invention relates to a novel monoalkylphosphine, and particularly, to a novel monoalkylphosphine useful for imparting flame retardancy, antistatic properties, etc. to fibers and plastics.
The present invention further relates to a method of producing monoalkylphosphine useful for imparting flame retardancy, antistatic properties, etc. to fibers and plastics, with good selectivity and yield.
2. Discussion of the Prior Art
Recentry there have been demands for highly-functional fibers and plastics having flame retardancy, the ability to modify resins, antistatic properties, etc. Organic phosphorus compounds, e.g., monoalkylphosphines such as methylphosphine, are used for these purposes. Methylphosphine is gaseous at room temperature under atmospheric pressure, and it will easily ignite and explode on contact with air. Methylphosphine is thus very dangerous and difficult to handle, and furthermore has high toxicity. Therefore, a monoalkylphosphine which is easy to handle and having low toxicity is desired.
It is disclosed that a polyester copolymerized with bis(2-carboxyethyl) methylphosphine oxide derived from methylphosphine exhibits good flame retardancy (U.S. Pat. No. 4,127,566). However, the copolymer thus produced has the faults that the melting point is significantly decreased, and that heat resistance is a little low.
The monoalkylphosphine of the present invention is a novel compound which improves on the above points, has excellent performance as a modifier for fibers and plastics, and can be easily produced with high purity.
A conventional method of producing monoalkylphosphine is through synthesis using a radical polymerization catalyst. However, this method produces a mixture of mono-, di- and trialkylphosphine due to reaction by a radical catalyst which has no selectivity, and thus high-purity monoalkylphosphine cannot be obtained even by purification distillation of the mixture. The method also has the disadvantage of low yield [J. Org. Chem., 26, 5138-5145 (1961)]. Unlike the present invention, the method produces a mixture of mono-, di- and trialkylphosphines having alkyl group substituent in the form represented by the following formula: ##STR2##
Another method by reaction of phosphine and an alkene in the presence of an acid catalyst is known [J. Org. Chem., 24, 356-359 (1959), U.S. Pat. No. 2,584,112]. Since this method uses as the acid catalyst an aqueous solution of alkanesulfonic acid, dialkylphosphine and trialkylphosphine are easily produced as by-products, and these by-products cannot be easily removed. Also yield is inevitably decreased due to side reactions.
As a result of extensive research on monoalkylphosphine as a flame retardant for polyester (U.S. Pat. No. 4,127,566, and Japanese Patent Laid-Open No. 52-33628) and useful as an intermediate of functional organic phosphorus compounds in consideration of the above-described facts, the inventors found a novel monoalkylphosphine compound.
The inventors also found that a high yield of high-purity monoalkylphosphine can be obtained without dialkylphosphine and trialkylphosphine by reaction of phosphine and an alkene in the presence of an organic solvent and anhydrous alkanesulfonic acid as a catalyst. The present invention has been achieved on the basis of that finding.